Method of manufacturing arms



April 22, 1941. .1. w. LEIGHTON METHOD OF MANUFACTURING ARMS Filed June 2, 1939 NE Y5.

Patented Apr. 22, 1941 UNITED STATES PATENT OFFICE 4 Claims.

" in cost of manufacture is of pronounced importance due to the fact that a tremendous number of suspensions are employed on automobiles.

The object of the invention is to provide a method of manufacturing an arm for an individual suspension or the like which will enable reducing the cost considerably, while still providing an arm having characteristics desirable in individual suspensions.

Other objects of the invention will become apparent from thefollowing specification, from the drawing to which it relates, and from the claims hereinafter set forth.

For a better understanding of the invention, reference may be hadto the drawing, wherein:

Figure 1 is a plan view with an arm adapted to be used in individual suspensions, which has been manufactured according to the principles of the invention;

Fig. 2 illustrates a length of straight bar stock from which the arm is to be formed.

Fig. 3 illustrates the shape of the bar after the ends are first bent;

Fig. 4 illustrates the step of axially upsetting the ends and simultaneously forming shoulders; and

Fig. 5 is a cross-sectional view, generally illustrating the dies that may be employed for axially upsetting the ends of the bar.

Referring to Fig. 2, rod or wire steel stock, in this instance uniformly round in section, is cut into predetermined bar lengths l0, and the ends of each bar are chamfered, as indicated at ll. Then the ends-of the bar are bent to provide end portions or stems l2 and I3 that are substantially parallel as shown. Confining dies 15, having openings substantially fitting the stems l2 and I3, are then applied to the latter as shown by Fig. l, and the depth of the openings and the length of the stem portions projecting thereinto are such that a short section of each stem adjacent the bend remains outside of the die openmg.

At the outer side of each bend, a die It is now provided and this die has a slot-like opening 18 which is open to the corner indicated at l9 so that the die may be moved downwardly over the bend to place the latter Within the opening. It will thus be noted that the lower end face of die l6 does not extend entirely around the bent portion of the stock, since the open side of the slot interrupts the end surface.

With the lower dies in the positions shown in Fig. 4, the upper dies I6 are now forced downwardly in directions axially of the stems, and since the lower dies prevent the confined metal stem portions against substantial expansion, the short lengths of stem between the bends and the upper ends of dies I5 are upset to form shoulders which are indicated at I]. This axial upsetting causes radial expansion of the metal rather uniformly although at the radially inner side of the bend it appears that there is greater resistance to radial expansion and the shoulder IT at this point is slightly decreased in extent. Moreover, and due to the fact that the slot in the upper die is open to the corner IS, the metal will flow towards the corner and increase the radial thickness of the bend. Thus, in addition to forming a shoulder [1 that generally is of about the same radial dimensions around the stem, the strength of the bar at the bend is increased.

One piece dies may be used in place of split dies l5 and thus each of the upper and lower dies may be of one piece construction. It will be appreciated that the lower die is of a confining character so as to prevent substantial expansion of the metal stem therein and that the upper die will hold the shape of the bend during application of the axial upsetting forces applied. The upper die is not a confining die in the sense that the lower die is of confining character, but undesirable flow of metal in the direction towards the corner I9 is apparently prevented by the metals resistance to compression or crowding at the inner side of the curvedsector.

Depending on size and other determinable factors, the bar may or may not be heated in the region of the bends. Under certain circumstances, the bar initially may be heated, then formed with the bent ends, and then upset while still heated. Under other circumstances, the bar may be bent and upset while cold.

Upsetting both ends at the same time is not only advantageous because of simplified manufacturing operations, but also because retention of both ends in confining dies maintains the bar in proper position, as the bar then cannot turn about the axis of either end or shank. It is to be understood that the lower confining dies will be anchored in predetermined relation. In this connection it is to be understood that the upper dies are to be moved together and simultaneously in a single support, to the end that a single movement of the support causes simultaneous formation of the shoulders at both ends of the bar. It will be appreciated that a bar with a single bend and upset shoulder at the bend may similarly be fabricated.

After this upsetting in an axial direction, each end of the stem outwardly of the shoulder ll is threaded, except for a small portion adjacent the shoulder. These threads are indicated at 28 in Fig. 1 and are of standard character, so that each of the threaded ends may be used as a pivotal trunnion which will be pivotal in a threaded opening.

' Following these manufacturing operations, the product'is heat treated for the purpose of ob taining the required strength, resiliency, and hardness adapting it to be employed for pivotally connecting a wheel support to a vehicle frame. This heat treatment provides the necessary hardness to ensure durability of the threaded bearing and desired resiliency to permit it to take sudden and excessive shocks without any danger of breakage.

It is to be appreciated that the upset shoulders may, as an example, be employed for retaining rubber sealing elements or rings that encircle the stems adjacent the shoulders.- By employ ing rod or wire steel stock, the number and cost of fabricating operations is practically minimized, because steel [conventionally is produced in-rod or wire stock that is readily available, and

this availability of the stock permits its purchase at lower price figures. Reduced to simpler terms, it is only necessary to out the bar to length, bend the ends by simple bending operations, axially upset both ends in a simple upsetting operation that can be done quickly, and then thread both ends, which likewise can be done rapidly. It may be observed also that formation of the shoulder after the bending operationavoids distortion of the shoulder as might occur if the shoulder were formed before the bending operation. Again, the procedure is simpler and less expensive than a drop forging method. Additionally, the invention is meritorious in that the working spaceis limited due to the shoulder being in close proximity to th bend.

Heat treatment of the bar is effected in a standard way well known in the art, except that the heat treatments are designed-to obtain the desired resiliency as well as bearing efficiency.

Although only one form of the invention has been described and illustrated in detail, it will be apparent to those skilled in the art that various modifications may be made without departing from the scope of the appended claims.

What is claimed is: I 1. The method of manufacturing an arm for use in automobile connections which comprises providing an elongate bar cut from bar steel 7 stock, bending the bar at one end to form an ofi- 3 set shank, confining the outer part of the shank in a die having an opening receiving said outer part of the shank so as to leave a non-confined shank section next to the bend in the bar, holding the bent section of the bar in a slotted die, the slotted portion of which receives the bend with the base of the slot substantially fitting the outer curved surface of the bend, and then relatively moving the two dies toward each other in a direction axially of the shank so as to upset and radially expand the non-confined shank section into a shoulder.

2. The method of manufacturing an arm for use in automobile connections which comprises providing an elongated bar cut from bar steel stock, bending the bar at each end to provide offset, substantially parallel shanks, confining the outer part of each shank in dies having openings receiving respectively said outer parts of the shanks so as to leave a non-confined shank section'next to each bend in the bar, engaging the outer curved portion of the bent por- .tions by slotted dies, the slotted portion of each die receiving the bend in the bar with the base of the slot substantially fitting the outer curved surface of the bend, and then relatively moving the two sets of dies in a direction axially of the shank so as to upset and expand the metal in the non-confined sections and form shoulders while holding the intermediate part of the bar and shank portions thereof firmly in their related positions. a

3. The method of manufacturing an arm for use in automobile connections which comprises providing an elongated bar cut from bar steel stock, bending the bar in one direction at one end to form an ofiset shank, with the shank joining the body of the bar through a single curved portion or elbow, confining the outer part of the shank in a die having an opening receiving said outer part so as to leave a non-confined shank portion adjoining the curved portion or elbow, applying a die member to the elbow with the member having a recess substantially fitting the surfaces of the elbow, and moving the die shank so as to expand the non-confined shank portion into a shoulder while substantially maintaining the shape of the elbow so that the sectional dimensions thereof are not 'reduce'dJ 4. The method of manufacturing an arm for use in automobile connections which comprises providing an elongated bar cut from bar steel stock, bending the bar in one direction at one end to form an ofiset shank, with theshank joining the body of the bar through a single curved portion or elbow, confining the outer part of the shank in a die having an opening receiving said outer part so as to leave a non-confined shank portion adjoining the curved portion or elbow, applying a die member to the elbow with such die member having a recess substantially fitting the outer surface portion of the elbow towards the outer convex side of the bend while leaving the inner elbow surface towards theconcave side of the bend non-confined, and moving the die members towards each other axially of the shank so as to upset and expand the nonconfined shank portion into a shoulder while substantially holding said" outerelbow surface against expansion but allowing expansion of the inner elbow surface to increase the radial thickness of the elbow.

JOHN W. LEIGHTON. 

